The Moon (idea)

Analysis of data from the Lunar Prospectorspacecraft in 1999backs the long existing theory that the Moon masses were ripped away from young Earth when an object the size of Mars ran into it. Parallels in the mineral composition of Earth and the Moon hint at a commonorigin. This similarity was already known. In the past, some scientists have translated this into an indication that Earth and the Moon had formed separately from the same cloud of rocks and dust.

The recent Lunar Prospector data shows however that the Moon has a smallcore that contains less than 4% of the Moon's total mass. Earth's iron core contains approximately 30% of the planet's mass. If Earth and the Moon had merely formed from the same blur of rocks and dust, the Moon would have a core comparable in proportion to Earth's, scientists claim. A much more liablethought is that a large body struck Earth, forcing a release of rocky matter from the outer shell into orbit, which collected to form the Moon.